An internal combustion engine designed so that the fuel injectors are connected to a common rail through high pressure lines and performing a plurality of fuel injections in a single cycle, for example two pilot injections and a succeeding main injection, is known (for example, see Japanese Unexamined Patent Publication (Kokai) No. 2000-18074). In this internal combustion engine, the main fuel injection is calculated from a map, and the injection amounts and injection timings of the first and second pilot injections are calculated from maps based on the main injection amount and the engine speed.
In such an internal combustion engine, however, if the fuel used changes, the fuel properties change. If the fuel properties change, the problems arise that deterioration of emission is invited or vehicle operability deteriorates.